This invention relates generally to rope guides for hoists and the like and more particularly to wire rope hoists having grooved drums. This does not exclude the possible use on other winding machinery that uses rope.
In a typical wire rope hoist installation the hoist assembly, consisting of a winding drum and a means for driving the drum, is mounted in a frame that is suspended on guide wheels which run on the flanges of an `I` beam. A standard crane hook that hangs on the wire rope below the hoist is the usual means provided for lifting loads.
The hoist is suspended above the work area at heights that often approach and sometimes exceed 100 feet.
Various methods of reeving the hoist to obtain the desired lift capacity and hook travel are employed, the simplest method being `single reeving` at standard load capacity where the hook moves from end to end of the hoist drum when raising or lowering a load. Another method called `double reeving` employs a right and left hand grooved hoist drum with the rope attached to one side then looped through a pulley assembly on the hook and attached to the opposite side of the drum. With this method the hook remains in line with the center of the drum throughout its operating height. In addition to these methods of reeving the hoist may also be multi part reeved to increase lifting capacity.
To reduce wear on the rope it is usual to have only one layer on the hoist drum and when multi part lines are used the drum length is increased considerably especially at greater operating heights. When the hoist is suspended parallel to the beam it is often not possible to operate the hoist near a wall or the end of the beam due to the length of drum. For this reason the hoist is sometimes suspended across the beam since its width is considerably less than its length. In this case it is necessary to `double reeve` the hoist so that load is always on the center of the beam.
Wire rope hoists are designed for vertical lifting only but often the operator will pull sideways to reach a load that is not under the hoist. This can cause the rope to jump the drum grooving causing damage to the rope and imbalance on the hoist particularly when it is suspended across the beam.
The foregoing illustrates limitations known to exist in present rope hoists. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.